Copper‐Nickel Tandem Catalysts for Selective Reduction of Carbon Dioxide to Ethylene by Stabilization of Cu+ via Tannic Acid

Electrochemical carbon dioxide reduction reaction (CO2RR) provides an effective method to convert CO2 into valuable C2+ products (e.g. C2H4) while mitigating atmospheric CO2 emissions. However, the C2+ performance is severely restricted by the sluggish C‐C coupling step during CO2RR. To this end, we have developed a tandem catalyst (namely Ni‐NC/CuTA) comprising Ni, N‐doped carbon (Ni‐NC) and TA (tannic acid)‐modified copper‐based component (CuTA). Ni‐NC component is primarily responsible for reduction of CO₂ to CO intermediates, which facilitate CO dimerization through improving the local CO coverage. CuTA component mainly executes C‐C coupling to boost C2H4 production in which Cu+ species stabilized by TA molecules synergize with Cu0 species to expediate C‐C coupling during CO2RR. The optimal Ni‐NC/CuTA catalyst produces C2H4 in a Faraday efficiency (FEC2H4) of 38.9% at ‐1.0 V (vs. RHE, RHE = Reversible Hydrogen Electrode) in a flow cell, surpassing the non‐tandem counterpart of CuTA (FEC2H4 of 23.9%) and XC‐72/CuTA (FEC2H4 of 19.9%), as well as the TA‐free Ni‐NC/Cu catalyst (FEC2H4 of 27.6%). Our work showcases that integration of tandem catalysis with Cu+/Cu0 synergism offers an efficient approach to accelerate C‐C coupling toward C2+ products.